use std::fmt::{self, Formatter, Display};

struct City {
    name: &'static str,
    // Latitude
    lat: f32,
    // Longitude
    lon: f32,
}

impl Display for City {
    // `f` is a buffer, and this method must write the formatted string into it.
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        let lat_c = if self.lat >= 0.0 { 'N' } else { 'S' };
        let lon_c = if self.lon >= 0.0 { 'E' } else { 'W' };

        // `write!` is like `format!`, but it will write the formatted string
        // into a buffer (the first argument) instead of the standard output.
        write!(f, "{}: {:.3}°{} {:.3}°{}", 
            self.name, self.lat.abs(), lat_c, self.lon.abs(), lon_c)
    } 
}

#[derive(Debug)]
struct Color {
    red: u8,
    green: u8,
    blue: u8,
}

fn main() {
    for city in [
        City { name: "Dublin", lat: 53.347778, lon: -6.259722 },
        City { name: "Oslo", lat: 59.95, lon: 10.75 },
        City { name: "Vancouver", lat: 49.25, lon: -123.1 },
        City { name: "Budapest", lat: 47.497222, lon: 19.040833 },
        City { name: "Paris", lat: 48.8567, lon: 2.3508 },
        City { name: "London", lat: 51.508531, lon: -0.076131 },
    ] {
        println!("{}", city);
    }

    for color in [
        Color {red: 128, green: 255, blue: 90},
        Color {red: 0, green: 3, blue: 254},
        Color {red: 255, green: 255, blue: 255},
    ] {
        // if we use {}, a compiler error will be reported:
        // `Color` cannot be formatted with the default formatter
        // println!("{}", color);
        println!("{:?}", color);
    }
}